2009-03-29

Spirit Sol 84

It's our last sol on Mars time. I spend a lot of the pre-shift time working ahead, trying to assess the terrain for our upcoming drive. Our long-term drive path is blocked by a rock I dub "Combover Pig," so we'll have to go southwest before we can head east to the hills. But there's a bigger problem in the near zone. I try to persuade myself that there's a short path to the other side of Mazatzal, but the terrain doesn't want to cooperate. There's a 15cm rock in the way -- which is not a hazard per se, but there's a 15cm-deep depression on the other side of the rock, making 30cm total, and that's an unsafe combination. I work on some ways to use the terrain against itself, putting one wheel up on the rock and straddling the depression, but there are worst-case scenarios no matter how we go. I'm almost willing to risk it anyway, but I run out of time to look at it without really reaching a resolution.

They used another one of my rover wakeup songs -- Cake's "The Distance" -- on Opportunity. This is because Opportunity set a new single-sol distance record: 48.9m. We're unlikely to surpass that record, but they will.

I've been worried whether we chose the right mesh yestersol, so I'm anxiously waiting around in the SMSA when the pass starts. The minute the images start flowing, John Grant walks up with a huge smile. "You made the right call," he says. The RAT placement was right on the money.

Mark points out that our image of the APXS doors, which is just intended to verify that the doors have closed after an APXS operation, was taken at a higher quality than we think is necessary. It's not a big deal, making only a few KB of difference in the downlink, but this piques my curiosity, and I go ask Justin Maki about it. He doesn't see any reason we need the higher quality either, but it's what they're doing on Opportunity, and it's simpler for everyone if we just let the missions be consistent. And since it's not a significant difference in the downlink volume anyway, we decide to drop it.

But this gets us into a discussion of documentation images. The more documentation images we take, the cooler Stubbe's movies will be. There's an opportunity to take more of them: every time we move the IDD when taking a series of MI images, we have to tell the rover to wait for 15 seconds so that any motion-generated vibration will stop before we take the microscopic image. Is there something else we could be doing in those 15 seconds?

Well, yes, there is. We could take a low-quality documentation image from the front hazcams. Justin does some back-of-the-envelope calculations and works out that we could take a halfway decent image in only 10-20 seconds of processing. And the images would be small -- we have to scale them down so that the rover can take them that quickly anyway -- so they wouldn't generate much downlink data.

Hmm.

Now, how to convince the project to take the images? We start scheming. Justin and Stubbe plan to show Stubbe's movie at thisol's downlink assessment meeting, and that's a perfect time to make the push. Our best idea is to have Justin tell the Spirit scientists, "Oh, they're going to start doing this on Opportunity" -- and then tell the Opportunity scientists, "Oh, we've been doing this for a while on Spirit." There's probably a lot of shit we could pull if we were willing to play the teams against each other this way.[1]

At the downlink assessment meeting, we get the official word that the RAT worked well. Better than that, indeed: the word they use to describe the placement is "perfect." The RAT ground away for almost 3.5 hours, just as planned, and dug 4.1mm into the rock. The yin-yang effect is gone; the surface is now nicely uniform.

Stubbe shows his movie, the history of our rover as seen through its front hazcams. The entire room gets into it in a big way. There are groans when we get stuck at Adirondack (The Time of the Great Anomaly), cheers when we get moving again. Good-natured laughs erupt when the rover's autonav gets spooked by hollows, and it does its little rover dance as it tries to find a path around the perceived hazard. "Hey, there's Humphrey!" someone calls out when the distinctive rock looms. I feel a thrill of pride when my then-record-setting drive goes by, a moment I missed yestersol. As the movie catches up to the present, the magnitude of what we've accomplished here starts to sink in. The movie ends, and the crowd bursts into applause. "That's our high-school reunion," Ray declares.[2]

Stubbe's made a similar movie for Opportunity and shows it as well; it's really cool, but it's not the same. It's somebody else's high-school reunion.

Thisol's IDD sequencing is moderately complex: a five-position MI mosaic of the new RAT grinding, followed by more MI observations on an interesting feature called "Hawaii" -- it looks like a pebble stuck in one of Mazatzal's scallops. After that, I need to place the APXS on the filter magnet, one of the magnets at the base of the mast -- a move that reminds me of placing your thumb on your nose. But it's one of those sols that's complex mainly because of the volume of the work, not because of tricky placements or anything like that, so it goes tolerably well.

Somehow I get drawn into an amusing Shakespeare-themed discussion -- "friends, rovers, countrymen"; that sort of thing. We run out of Shakespeare-oriented rover jokes about as fast as you'd expect engineers to, and I get back to work. But it reminds me of something I worked out early in the mission:

Two rovers, both alike in dignity, From Pasadena, where we build such things, From launching pads break forth to neighbors planet'ry, Where Martian dust makes solar pan'ls unclean. From forth the IDDs of these two bots A scientific package springs to life.

On my way out, there's bad news from the other side of Mars: Opportunity is having some kind of anomaly. Sounds like the EEP[3] failed and they lost a sol's sequences; no telling how bad it is. Nothing I can help with, though, so I cross my fingers for them and go home.

Courtesy NASA/JPL-Caltech. Combover Pig. But I couldn't talk anyone else into the name. Is it just me? It totally looks like a pig with a combover, right?

"I'll not meddle with [my conscience]: it is a dangerous thing: it makes a man a coward: a man cannot steal, but it accuseth him; he cannot swear, but it cheques him; he cannot lie with his neighbour's wife, but it detects him: 'tis a blushing shamefast spirit that mutinies in a man's bosom; it fills one full of obstacles: it made me once restore a purse of gold that I found; it beggars any man that keeps it: it is turned out of all towns and cities for a dangerous thing; and every man that means to live well endeavours to trust to himself and to live without it." -- Richard III, I.iv.

Also, it makes you not talk one rover team into doing something by telling them the other rover team is already doing it, no matter how cool it would be. Damn conscience.

5 comments:

Hi Scott, every day I look forward to reading this blog; it is fascinating to get an insider's view of such a project. And I admire your writing skills.

A minor technical hiccup: I remember two weeks ago having the feeling that there were two blog entries published the same day, but I didn't think any further about it - until today, when I recognised the "feeling" of today's Sol 84 entry. Doing a search for "conscience" in my Google Reader it turns out that today's entry was already visible there dated March 15'th, wedged in between Sols 70 and 71.

Thanks a LOT for this blog!!! Still revives the 5-year old memories, even though they don't really need reviving - everything is as fresh as yesterday.

On a particular note - sometimes it helps to be an outside observer - I did not have to side with one team vs. another, and could equally enjoy the adventures on both sides of the planet, equally cheering for both teams :-)

@Hans Glad you're enjoying it, and thanks for the compliments (you, too, Andrew!). In Blogger, I occasionally reflexively hit "Publish" when I mean to schedule the post for the future -- I catch it right after, but I think it sometimes shows up in the RSS/Atom feed anyway. Argh.